#include<stdio.h>
char* mystrcat(char* arr1,const char* arr2)
{
    char* arr3=arr1;
    while(*arr1!='\0')
    {
        arr1++;
    }
    while(*arr2!='\0')
    {
        *(arr1++)=*(arr2++);
    }
    return arr3;
}
int main()
{
    char arr1[20]="hello";
    char arr2[20]="bit";

    char* arr3=mystrcat(arr1,arr2);
    printf("%s",arr3);
    return 0;
}